Arrowverse Crossover Video Goes Behind the Scenes of Invasion!

The CW’s big superhero crossover event has begun. Starting with Supergirl on Monday, then leading into The Flash,Arrow and Legends of Tomorrow the rest of the week, all four shows in the network’s Arrowverse will finally come together with its heroes facing a race of aliens known as the Dominators. While Supergirl’s Earth has its fair share of aliens already, the action actually kicks off on The Flash, when Barry Allen (Grant Gustin) is forced to seek out Kara Danvers (Melissa Benoist) and ask for her help.

The crossover story itself is loosely based on the 1980s comic book miniseries Invasion, and it was actually quite an undertaking for the cast and crew to bring to life. It’s taken six months of planning to take the story from script to screen, not to mention the work on “cutting-edge prosthetics and computer effects” that executive producer Marc Guggenheim says were used for the Dominators “to achieve a feature film-quality look which is faithful to Invasion! artist Todd McFarlane’s interpretation of the characters.” A new behind the scenes featurette above gives viewers a first look at possibly the biggest crossover ever done on TV.

A cast including more than 10 superheroes and friends filled Boundary Bay Airport back in October to film the big introduction scene where everyone comes together for the very first time. For most of the characters, Supergirl is the odd one out, as this is the first time she’s been to Earth-1 and met Oliver Queen (Stephen Amell) and the rest of the gang. There’s a lot of challenges with having so many actors in one room, plus the logistics of scheduling them all for their scenes across multiple different shows. It was quite an undertaking for everyone, but we’re sure fans will agree it was all worth it once its aired.

Arrow‘s episode of the crossover also just so happens to be the series’ 100th, which means it had its own requirements to commemorate this big milestone. Actually, each episode of the crossover not only had to introduce its characters, tie into the overall invasion story, but also stand on its own and carry each show’s overall arc. For Arrow, that meant bringing back a number of characters from the show’s past. Guggenheim says Berlanti came up with an idea that “is a love letter to the show. It draws on all previous 99 episodes, pretty much. Everyone who we could have in the episode from a scheduling point of view is in the episode. Even the people who we couldn’t have because of conflicting schedules are represented.”

The crossovers won’t end after this week either. A Supergirl and The Flash musical crossover is planned for later in the season. And the Dominators are set to appear again on Supergirlsometime in the new year. While the second one probably won’t be a crossover exactly, it does mean that a part of Earth-1 will be coming over to Kara’s world after all is said and done. The most important thing coming out of this crossover is that Supergirl is truly now part of the DC TV universe.

‘Invasion!’begins Monday, Nov. 28 with Supergirl at 8 p.m. EST on The CW, and continues with The Flashat the same time on Tuesday, Arrow on Wednesday, and Legends of Tomorrow on Thursday.